Kalinin was assigned to the yard of the airline Ukrvozdukhput after the registration of the K-1 design in Kharkiv as a construction site.
The yard was then renamed GROS (Graschdanskoje Opytnoje Samoleostrojenie, pilot aircraft construction for civil aviation).
The fuselage consisted of a welded tubular steel framework and was clad with light-alloy sheet metal from Koltschug aluminum.
The wings had an elliptical shape and were, like the tail, made of tubular steel and also covered with light metal sheets.
Data from The Osprey Encyclopedia of Russian Aircraft 1875–1995[1]General characteristics Performance